Strength of Helical Springs.
425
Gd
C^4
oe referred to radius r (Fig. 378) if w be increased.
Strength Tm a d*, while stiffness ~ a d*.
&i.-The angle of torsion of a round W. I. shaft is to
^ for every 3 feet of length, and the maximum stress is
- per sq. in. Find the one diameter to satisfy both con-
rxs. Mach. Constr. Exam. 1889.) (See App. K, p. 997.)
22X2 2X8000X36 .
-_. or -, -----------^ ^ d^^'i&i
O d 7x360 10,500,000, xd
'f ** <3L1 £&mThe angle of torsion being limited to one degree
IO feet of length, find the diameter of shaft to transmit
*t K£O revs. perm. (Hons. Applied Mech. Exam. 1892.)
22X2 2X/XI2O
7x360" 10,500,000 xd
100
^3 =
7x50
and /= 763*8 <f
and/=^2-°
763-8^ =
641,620
and
of Helical (Spiral) Springs.In the round
.(Fig-. 379) the pull is exerted axially, and any
f if* In torsion.
16
Extreme elastic stress for steel =89,000 Ibs.
_ . . 89,000 .,
oxid. working stress = ^ - = 29,600 IDS.
o
«|tiatre-sectioned steel (Fig. 380),
sections,
421.)